Hygrometer



Nov. 29, 1938. .R. A. NEEDHAM 2,138,707

HYGROMETER Filed May 24, 1957 CALENDER FOR ATTO R N EYS Patented Nov. 29, 1938 UNITED STATES PATENT OFF HIE;

Claims.

My invention relates to hygrometersand includes among its objects'and advantages the provision'of a'novel device formeasuring and registering the moisture content of the surrounding atmosphere.

In the accompanying drawing:

Fig. 1 is a perspective View of the front face of my invention;

Fig. 2 is a perspective view of the rear face;

Fig. 3 is a sectional view along the line 3-3 of Fig. 2;

Fig. 4 is a sectional view along the line 4-4 of Fig; 3; r, Fig. 5 'is of Fig. 2;

Fig. 6 is a fragmentary detail view;

Fig. '7 is asectional View along the line 7-7 of Fig. 3; and

Fig. 81s a sectional view along the line- 8-8 20 of Fig. 3.

In the embodiment selected to illustrate my invention I make use of a sheet of cardboard ID of 8 or 10 ply thickness which may, for example, be 11 by 14 inches; The grain of the paper runs 25*horizontally when viewing Figs. 1 and 2. In Fig. 1, I illustrate the sheet H] as a support for the calendar [2, and the additional space may be utilized for advertising purposes.

Upon the rear face of the sheet I0 I mount an 30 indicating needle I4. This needle includes a pointed end IB exposed through a sight opening I8 and arranged in reading relation with the indicia indicating atmospheric conditions in terms of moisture content. Referring to Fig. 8,

35 the needle I4 is provided with an opening 22 fitting snugly but loosely upon a pin 24 which extends through an opening 26 in the sheet In. A washer 28 is mounted on the pin 24 adjacent the front face of the sheet In while a spacing sleeve 0 30 is positioned between the needle l4 and the rear face of the sheet. The pin 24 includes a reduced shank 32 for the reception of a washer 34. The pin 24 is riveted at its ends, as indicated at 36, for connecting the parts in assembled rela- 45 tion. Sleeve 30 holds the needle in spaced relation with the rear face of the sheet l0 so as to permit free movement of the needle about the pin as an axis.

A wire 38 has one end hooked at 40 and passed 50 through an opening 42 in the needle l4 in close relation with the pin 24. The opposite end of the wire 38 is bent to provide an eye 44 through which a bolt 46 extends. Bolt 46 passes through a slot 48 in the sheet l0 and includes a head 50 55 bearing against the front face of the sheet. A

a sectional viewalong the-line 5-5 nut 52 has threadedrelation'with'thebolt'for:

holding the eye 44 in assembled relation'therewith. Slot 48 permits the bolt 46-to=be adjusted ing strips 56"adhesi-v'ely secured to the rear face Strip 54 extends across the sight opening 38 in such spaced relation with-'the-sheet' 3- as to permit the needle M to pivot freely:-

of the sheet"! 8.

Strip 54 affords protection for theneedle-to pre= vent accidental bending; as when" handling and packaging, and holds'the'needlein spaced'rela-- tion with the wall or other support for thesheet I prefer tomakethe strip 540i the samematerial as the sheet Hiso-as to-have thesame co'- eihcient of expansion. The face of=the-strip54 adjacent the sheet It may be white in color'with" the visible portion ofthe needle colored black to facilitate reading.

the same as the visible face of the sheet I0? To each of the vertical edges of the sheet [0 I connect a Ushaped metallic strip 58. The margins of the vertical edges are pinched lightly between the flanges of the strips, which strips operate to prevent curling of the sheet I0. While the strips 58 prevent buckling of the sheet ID, the sheet may expand and contract freely so as not to impair its reaction to variable moisture content. The pinching relation between the strips and the vertical edges of the sheet is merely sufiicient to hold the strips in connected relation with the sheet, thus permitting free expansion and contraction.

An endless cord 60 passes through openings 62 in the sheet and may be hooked over a. supporting pinv 64.

In operation, the device reacts to the action of moisture on the paper sheet l8. Increased moisture content of the air causes the paper to lengthen while decreased moisture content will cause the paper to shrink and shorten. Such lengthening and shortening of the paper is indicated and amplified by the movement of the points IS with respect to the indicia 20. The indicia may be in terms of percentages of moisture, as indicated in Fig. 1. Considerable amplification in the shifting action of the pointed ends I6 is attained because of the relation between the pivotal axis of the needle l4 and the wire 38.

[4. Eye 44 may be Other contrasting colors may be-employed and the color of thestrip 54-may be- A device according to my invention is sensitive to the slightest changes in moisture content in the air. The device may be manufactured at a relatively low cost and embodies a novel and accurate mechanism for registering relative humidity. The sheet 10 while constituting a part of the hygrometer provides a relatively large area for advertising purposes.

Without further elaboration, the foregoing will so fully explain my invention that others may, by applying current knowledge, readily adapt. the same for use under various conditions of service.

I claim:

1. A hygrometer comprising a sheet having such properties as to lengthen or shorten in response to variations in the moisture content in the surrounding atmosphere, said sheet being provided with a sight opening and moisture indicating ratios on its front face, a needle located on the rear face of the sheet and pivotally mounted thereon, said needle having a point exposed through said sight opening, said needle being pivotally connected near one end of the sheet, and a link having one end pivotally connected with the needle and its other end attached to the sheet near the opposite end thereof.

2. A hygrometer comprising a sheet having such properties as to lengthen or shorten in response to variations in the moisture content in the surrounding atmosphere, said sheet being provided with a sight opening and moisture in- .dicating ratios on its front face, a needle located on the rear face of the sheet and pivotally mounted thereon, said needle having a point exposed through said sight opening, said needle being pivotally connected near one end of the sheet, a link having one end pivotally connected with the needle and its other end attached to the sheet near the opposite end thereof, and a guard car- 'ried by the rear face of the sheet for protecting provided with a sight opening and moisture indicating ratios on its front face, a needle located on the rear face of the sheet and pivotally mounted thereon, said needle having a point exposed through said sight opening, said needle being pivotally connected near one end of the sheet, a link having one end pivotally connected with the needle and its other end attached to the sheet near the opposite end thereof, and means for adjusting the link, to permit the needle to be accurately adjusted with respect to said indicia.

4. A device of the type described comprising asheet having such properties as to lengthen and shorten in response to moisture content of the surrounding atmosphere, an indicating needle pivotally mounted on the sheet, moisture indicia on the sheet in operative relation with the needle, an operating connection between the sheet and the needle for imparting pivotal action to the latter in response to lengthening and shortening of the sheet, metallic liners along two opposite edges of the sheet, said metallic liners being U-shaped in cross section and having pinching relation with the sheet, to prevent buckling thereof, but operating to permit free expansion and contraction of the sheet.

5. A hygrometer comprising a sheet having such properties as to lengthen or shorten in response to variations in the moisture content in the surrounding atmosphere, said sheet being provided with a sight opening and moisture indicating ratios on its front face, a needle located on the rear face of the sheet and pivotally mounted thereon, said needle having a point exposed through said sight opening, said needle being pivotally connected near one end of the sheet, a link having one end pivotally connected with the needle and its other end attached to the sheet near the opposite end thereof, and a guard carried by the rear face of the sheet for protecting the needle, said guard extending across the sight opening with the needle positioned between the guard and said sheet, said guard and the needle having contrasting colors.

RALPH A. NEEDHAM. 

